Motor control for irrigation apparatus

ABSTRACT

To provide for an automatic restart of an irrigation system after a power failure and the motor has stopped a motor driven adjustable timer closes a contact after a preset time interval. The contact completes a circuit in a control panel effective to cause the system to resume operation.

United States Patent 1 1 3,764,852 Olson Oct. 9, 1973 MOTOR CONTROL FORIRRIGATION APPARATUS Primary Examiner.l. D. Miller AssistantExaminerl-larvey Fendelman [76] Inventor: Rich L. Olson, R. R. 1, Box83,

scottsbluff, Nebr' Attorney-McDougall, Hersh & Scott [22] Filed: June 9,1972 317/13 317/36 307/1414, To provide for an automatic restart of anirrigation 317/141 R system after a power failure and the motor has [5l] Int. Cl. H02h 7/085 stopped a motor driven adjustable timer closes aconnew of Search 317/13 13 141 tact after a preset time interval. Thecontact com- 317/36 TD; 84; 307/141 pletes a circuit in a control paneleffective to cause the system to resume operation. 5 6] References CitedUNITED STATES PATENTS 3 Claims, 3 Drawing Figures 2,444,295 6/1948Kaiser 317/13 A i it 64 L F I 6,2\, 3w f -66 68 M 1- t SHEET 2 BF 2MOTOR CONTROL FOR IRRIGATION APPARATUS BACKGROUND OF THE INVENTION Thisinvention relates generally to improvements in irrigation apparatus.More specifically, it relates to improvements in the circuit forcontrolling the pump motor forming a part of such apparatus.

Irrigation systems drawing upon water pumped from wells have come intoextensive usage. The water so pumped may be supplied to either a mobileor stationary system. In a typical mobile system use is made of a maindistributor which may be as much as one-half mile in length. An innerend of the pipe is connected to a water source, that is, a pipeextending into the ground connected in turn to the outlet of a submergedcentrifugal pump to provide a source of water under pressure tosprinkling heads along the length of the pipe for sprinkling the wateron crops in a field being irrigated. Usually, the distributor pipe ismounted for rotation about a central pivot where the inner end isconnected to the water source. A plurality of driven towers spaced alongthe distributor pipe support it and carry it across the field. Astationary irrigation system would include sections of pipe which aremanually moved from one field section to another as desired.

Not infrequently, there are interruptions in the electrical systemssupplying such systems. The interruptions can occur at any point in autility companys distribution network as a result of lightning strikingtransformers or lines, overloads or simply because of equipment failure.On farms of the size wherein mobile irrigation systems of the typedescribed are used the farm operator depends upon the control system tomaintain and monitor the operation of his irrigation system and were itsoperation to be interrupted as the result of a power failure he mightnot even be aware of it and an irrigation schedule would be seriouslydisrupted and perhaps not even completed.

Insofar as the applicant is aware, while some prior art systems haveprovided for automatic restart of the pump motor under the circumstancesdescribed they have all provided for an instantaneous restart. It hasbeen found that under certain conditions with instantaneous restart thesystem can be damaged. To appreciate this it must be understood thewells used to supply water may extend to depths of 300 to 600 feet. Amotor at the top of the well, ranging from 50 to 300 horsepower, drivesa turbine pump at the bottom of the well casing by means of a shaftextending downwardly through the casing and supported by bearings spacedover its length. While the motor is operating, the pump maintains acolumn of water of substantial length in the delivery pipe and of coursemore water is present in the irrigation system itself. If the motorshould stop as the result of a power failure or otherwise, the water inthe pump delivery pipe and probably that in the irrigation system willfall to the bottom of the well toward the pump with substantial forcedue to its weight and the fact that it is accelerating over asubstantial distance. Were the pump motor to restart under thesecircumstances it would be attempting to restart and pump water in theface of a substantial load. The result could be damage to the pump ordamage to the motor or;

both.

Another problem can arise when there is an attempt to instantaneouslyrestart a pump motor as described,

if the power failure was caused by lightning striking a portion of autility's electrical distribution network, and the utility is working toreestablish that network or an alternate. If as switches are cuttingback in and various circuit protectors are monitoring the load and oneof the loads immediately appearing on the line is the demanding load ofa relatively large electric motor, it is possible that the circuitprotectors may cut out hampering the utilitys ability to reestablish andstabilize the distribution network.

Accordingly, it is an object of this invention to provide a novelautomatic circuit for restarting a pump motor after a power failurewhich by delaying the restarting for a time interval after power isrestored enables a utility network supplying the pump motor to becomestabilized before the motor is put on the line.

SUMMARY OF THE INVENTION The foregoing and other objects are achieved byproviding a motor contact circuit effective upon the restoration ofpower after a power failure to complete a circuit to an irrigation pumpmotor at a predetermined time after power has been restored.

BRIEF DESCRIPTION OF THE DRAWINGS While the invention itself is definedin the claims forming a part of this specification, an understanding ofthe construction and mode of operation of an embodiment may be derivedfrom the attached description taken in conjunction with the drawings inwhich:

FIG. 1 is a perspective view of a mobile irrigation system embodying theinvention, showing the pivot end and the outer end section with theintervening portions omitted;

FIG. 2 is an illustration of a control circuit for a mobile irrigationsystem incorporating the invention; and

FIG. 3 is a schematic diagram of a motor circuit controlled inaccordance with the invention.

DETAILED DESCRIPTION FIG. 1 illustrates a mobile irrigation systemwherein a distribution pipe extends from a central pivot. However, itshould be understood that the system illustrated is for purposes ofexemplification only for it is contemplated that any irrigation systemderiving water from a pumped well may be improved in accordance with theinvention.

Referring now to the drawings for a description of the invention, thenumeral 10 indicates the elongate horizontally disposed waterdistribution pipe which is provided with a swivel connection 12 at itsinner end for pivotal attachment to the upper end of a feed pipe whichmay extend downwardly to a well in the ground or which is otherwisesupplied with water under pressure for irrigation, as from a stream,well or other source of water. Thus, the feed pipe 14 represents theaxis about which the water distributor pipe turns. Other means forpivotal attachment in sealing engagement between the distributor pipeand the feed pipe are well known by reason of the widespread utilizationof such an arrangement in commercial practice.

The distributor pipe 10 is provided with a plurality of spray nozzles 16at frequently spaced intervals along the length of the pipe foroperation as overhead sprays to sprinkle water onto the crop as thedistributor pipe moves about the feed as its axis. The distributor pipeis supplied with water under pressure, as by means of a water pumpconnected with a supply pipe or water tower.

A number of mobile towers T are arranged in longitudinally spaced apartrelation along the length of the distributor pipe with means forengaging the adjacent portions of the pipe for support. The number ofmobile towers T can be varied depending somewhat upon the spacedrelationship between supports and the length of the distributor pipe.The distributor pipe can be suspended from the support by means of acable so as to be carried by the support.

To maintain automatic alignment of the towers a flexible cable 18 whichis fixed at its inner end 20 to an arm 22 which extends laterally fromthe pivot while the outer end 24 is fixed to the end portion ofalaterally extending cross beam 28 on the outermost tower so that theflexible cable 18 will extend in essentially a straight line from saidpivot to said outermost tower.

The flexible cable is threaded through an opening in a pendulum 30 thatis mounted on each of the intermediate towers for free rocking movementabout an axis which is parallel with the axis of the pipe and in adirection crosswise of the distributor pipe. The pendulum 30 comprisesan elongate member which is suspended to depend from the tower on apivot pin extending laterally from the end portion of a horizontallydisposed cross brace member 32 rigid with the tower.

When the intermediate mobile tower is in proper alignment, the pendulumwill be suspended from its pivot to hang downwardly substantiallyperpendicularly so that the pendulum will be free of the plunger of aswitch controlling the tower drive motors.

A control system in accordance with the invention is illustrated in FIG.2. Power for the control system and for operation of the variouscomponents including the pump motor and tower motors is derived via athree wire three-phase connection 40 to the output of a three-phasedistribution network. A manually-operated power disconnect 42 isprovided for operation by a user when it is desired to connect ordisconnect the system to the line. Conventional protection againstthermal or current overload may be provided by fuses 44.

Supplied from the line 40 are the motors on each of the towers T, onlyone of which, 46, is shown, it being understood that each tower has aseparate drive motor. Mounted on each tower is a control panel 48,which, forms no part of this invention but, is constituted by well knownelectrical devices effective to start and stop the tower motor 46 andconnect the line 40 to the next tower by means of the conductors 50.Each tower control panel responds to timed control signals transmittedby means indicated at 52 from a control panel 54 mounted on or adjacentto the pivot tower. Basically, the signal from panel 54 determines thedirection of rotation of the tower motors 46 and their time ofoperation. To this end the panel 54 includes forward and reverse relays(not shown) which also determine whether a switch 58 for forwardoperation or a switch 60 for reverse operation is to be closed.

Power for the pivot control panel 54 and tower control panels 48 isderived via a stepdown transformer 62, the primary 64- of which isconnected across the line 40 while the secondary 66 is connected betweena ground or neutral bus 68 and supply bus 70. In a preferred embodimentit is contemplated that line 40 may be supplied 460 volt three-phase 60hz for the tower motors 46 when the output of the transformer is 120volt single-phase 60 hz.

Included on the control panel 54 is a start switch 72 having at leastone contact which when closed momentarily connects coils 74 and 76across and 68 to cause those coils to be energized. Other contactsassociated with the switch 72 (not shown) cause other elements (notshown) in the control panel 54 to become appropriately energized so thatthe pivot towers will function as desired as the result of signalsderived via 52.

The coil 74 is part of a relay and when energized closes a holdingcontact 78 to maintain a circuit shunting switch 72 which as stated isclosed only momentarily. The coil 76 (see FIG. 3) may be the coil ofpilot relay or the coil in a contactor 80 connected in a line 82supplying a three-phase pump motor 84 and when energized closes thecontactor to energize the motor. A shaft 86 from the motor 84 located atthe well head drives a pump 88 having an intake 90. The pump output isconnected to the pipe 14 which in turn is connected to the distributorpipe as described.

Referring again to FIG. 2, a control system in accordance with theinvention includes a motor driven timer 92 comprising a timer motor 94capable of operating a pair of contacts 96 and 98 through anelectromagnetically controlled clutch 100. As may be seen, the clutch isconnected in series with the transformer secondary 66 so as to beenergized whenever the power disconnect 44 is closed and power is beingsupplied to the line 40. The motor 94 is in series with the contact 96between the bus 70 and ground 68. A relay coil 102, operating a contact104 shunting the start switch 72, is connected in series with contacts96 and 98 between the bus 70 and ground 68.

The motor driven timer 92 can be of any one of a number of commercialdevices arranged to operate the contacts 96 and 98 at predeterminedtimes when the motor and clutch are energized. The particulararrangement used herein is one, when the clutch is energized and themotor runs because contact 96 is in the position shown, after apredetermined time interval fixed by setting a pointer on a dial, thecontact 98 will close and the relay 102 will pick up and a short timelater the contact 96 is opened to deenergize the motor and cause relay102 to drop out. If the solenoid controlling the clutch 100 should dropbecause power to it is interrupted the contacts 96 and 98 will beautomatically reset to positions shown in FIG. 2 by suitable returnsprings.

The time delay means just described operates to control the pump motorcircuit as follows: The normally opened contact 104 forming a part ofrelay 102 shunts the start switch 72. When the relay 102 picks up thecontact 104 closes energizing the coils 74 and 76. The energization of74 closes contact 78 to complete a holding circuit while theenergization of 76 closes the contactor 80 in the pump motor circuit sothat pumping will commence.

Assuming system start-up under normal circumstances, the disconnect 42is closed and the various settings on the control panel 54 aredetermined by the operator and he then depresses start switch 72 to putthe system into operation. Prior to this because the clutch 100 wasdeenergized the contacts 96 and 98 were in the positions shown in FIG.2. At the time disconnect 42 was closed the timer 92 began to time outbecause clutch 100 became energized as did the motor 94. After apredetermined time the switch 98 closes picking up relay 102 which inturn closed 104. However, nothing happens in the pump motor controlcircuit because the coil 76 had already been energized by closing thestart switch 72 and the completion of the holding circuit throughcontact 78. A short time later a contact 98 closes, the contact 96 opensdeenergizing the motor 94 and relay 102. At this point the systemremains as is until the clutch 100 is deenergized and the contacts 96and 98 are then reset to the positions shown. It is to be noted that thetimer and the contacts controlled thereby cycle through once each timepower is applied to the system and are reset upon interruption of power.

Assume therefore that system is operating with coils 74 and 76 energizedthrough holding contact 78 and there is a power failure. Holding relay74 drops out and clutch 100 is deenergized while disconnect 42 remainsclosed. The tower motors 46 and pump motor 88 stop and water begins todrain back into the well. When power is restored, clutch 100 isenergized as is the motor 94. As before, after a predetermined timecontact 98 closes, relay 102 closes contact 104, relays 74 and 76 pickup restarting the pump motor and putting the system back in operation.

For all the reasons stated previously the provision of a time delayafter restoration of power is important and is provided hereby. Asdescribed, the time delay restart circuit cycles once for each powerrestoration. In addition, it is fail safe for the failure of anycomponent will not cause the pump motor to start prior to a timeintended.

Various modifications can be made in the invention without departingfrom the spirit thereof and it is intended by the claims to cover allmodifications and changes from the embodiment disclosed, as come withintheir scope.

What is claimed as new and desired to be secured by Letters Patent is:

1. An irrigation system including: a water distribution means; means forconnecting said distribution means to a source of water; a pump forpumping water through said connecting means and said distribution means;first means for connection to a source of electric power; an electricpump motor for driving said pump; a power circuit connected between saidfirst means and said motor for supplying power to said motor; a controlcircuit; second means coupling said control circuit to said first means;said control circuit comprising a timer motor, an electromagnetic clutchconnected to said second means and to said timer motor, first and secondcontact means connected to said clutch to be operated in response to therotation of said timer motor, said first contact means connecting saidtimer motor to said second means to cause it to be energized when poweris supplied from the source of electrical power and to cease operationwhen said first contact means has operated after a predetermined timeinterval in response to the rotation of the timer motor, said secondcontact means operating after a predetermined time interval in responseto the operation of said timer motor to provide an output, and meansconnecting the output to said power circuit to cause said pump motor tobe energized.

2. In the irrigation system of claim 1 wherein said output isconstituted by a relay having a coil energized in response to operationof said second contact and whereby said means connecting said output tosaid power circuit comprises a relay contact controlled by said relayand a circuit controlled by said relay contact to close said powercircuit to said pump motor.

3. In an irrigation system including: a motor distribution means; meansfor connecting said distribution means to a source of water; a pump forpumping water through said connecting means and said distribution means;an electric motor for driving said pump; a power circuit connected tosaid motor for supplying power to said motor; and a control circuit forcontrolling said power circuit; the improvement in said control circuitcomprising a time delay circuit; said time delay circuit comprising anelectromagnetically-controlled clutch; means for connecting said clutchto said power source whereby said clutch will be energized wheneverpower is available from the source; a timer motor having a shaftconnected to said clutch; means for connecting one side of said motor tosaid power source; a first contact connecting the other side of saidtimer motor to said source; a relay; means for connecting one side ofsaid relay to said source; a second contact; means for connecting theother side of said relay to said second contact; means for connectingsaid second contact to said first contact; said first and secondcontacts mounted to be operated when said clutch and said timer motorare energized; a relay contact operated by said relay; and control meansoperating in response to the closure of said relay contact to connectthe power circuit to said motor.

1. An irrigation system including: a water distribution means; means forconnecting said distribution means to a source of water; a pump forpumping water through said connecting means and said distribution means;first means for connection to a source of electric power; an electricpump motor for driving said pump; a power circuit connected between saidfirst means and said motor for supplying power to said motor; a controlcircuit; second means coupling said control circuit to said first means;said control circuit comprising a timer motor, an electromagnetic clutchconnected to said second means and to said timer motor, first and secondcontact means connected to said clutch to be operated in response to therotation of said timer motor, said first contact means connecting saidtimer motor to said second means to cause it to be energized when poweris supplied from the source of electrical power and to cease operationwhen said first contact means has operated after a predetermined timeinterval in response to the rotation of the timer motor, said secondcontact means operating after a predetermined time interval in responseto the operation of said timer motor to provide an output, and meansconnecting the output to said power circuit to cause said pump motor tobe energized.
 2. In the irrigation system of claim 1 wherein said outputis constituted by a relay having a coil energized in response tooperation of said second contact and whereby said means connecting saidoutput to said power circuit comprises a relay contact controlled bysaid relay and a circuit controlled by said relay contact to close saidpower circuit to said pump motor.
 3. In an irrigation system including:a motor distribution means; means for connecting said distribution meansto a source of water; a pump for pumping water through said connectingmeans and said distribution means; an electric motor for driving saidpump; a power circuit connected to said motor for supplying power tosaid motor; and a control circuit for controlling said power circuit;the improvement in said control circuit comprising a time delay circuit;said time delay circuit comprising an electromagnetically-controlledclutch; means for connecting said clutch to said power source wherebysaid clutch will be energized whenever power is available from thesource; a timer motor having a shaft connected to said clutch; means forconnecting one side of said motor to said power source; a first contactconnecting the other side of said timer motor to said source; a relay;means for connecting one side of said relay to said source; a secondcontact; means for connecting the other side of said relay to saidsecond contact; means for connecting said second contact to said firstcontact; said first and second contacts mounted to be operated when saidclutch and said timer motor are energized; a relay contact operated bysaid relay; and control means operating in response to the closure ofsaid relay contact to connect the power circuit to said motor.